A close look at trilobite fossils suggests that a type called olenid trilobites farmed bacteria, says a London researcher.
These extinct arthropods plied the oceans some 505 million to 445 million years ago, explains Richard Fortey of the Natural History Museum. In the June 6 Proceedings of the National Academy Of Sciences, he proposes that the animals survived on the ocean floor thanks to bacteria that can use sulfur for energy. If he's correct, these trilobites would be the earliest creatures known to have forged a partnership with another species.
The trilobite's body plan provided ample space for bacteria on its legs and wide thorax. A feeding structure seems to have atrophied in the olenid group, as if its members no longer needed to take in food. Also, these trilobites had brood pouches, Fortey says. That recent discovery fits the notion that parents protected their young until the little trilobites could establish their own bacteria gardens.